Mesothermal and Microthermal Climates

Summary

This lecture explores mesothermal and microthermal climates, focusing on their characteristics and geographical distribution. Mesothermal climates, found in the mid-latitudes, experience mild winters and significant weather variability, with notable subtypes such as humid subtropical, marine west coast, and Mediterranean dry-summer climates. Microthermal climates, located in mid to high latitudes, are colder, with long, harsh winters and cool summers. The lecture explains the factors influencing these climates, including latitude, air masses, and continentality, and highlights the differences in precipitation patterns and temperature variations between these regions.

Takeaways

• 😀 Mesothermal climates are found in mid-latitudes and are characterized by mild winters and moderate seasonal extremes.
• 😀 About 27% of Earth's surface is covered by mesothermal climates, and over 40% of the global population lives in these regions.
• 😀 These regions are typically humid, except where subtropical high pressure causes dry summers, leading to greater weather variability.
• 😀 Air masses from source regions meet in mesothermal climates, creating weather patterns like fronts, lifting, and precipitation variability.
• 😀 Day length and insolation vary more significantly in mesothermal climates, with some areas experiencing very long days and short days in other seasons.
• 😀 Humid subtropical climates feature hot summers, maritime air, convectional showers, and fronts created by the meeting of tropical and polar air masses.
• 😀 Marine west coast climates are known for cool, moist weather, coastal fog, and mild winters with cool summers, influenced by maritime polar air masses.
• 😀 Mediterranean dry-summer climates are rare, with precipitation concentrated in winter, and dry summers due to high-pressure systems blocking moisture.
• 😀 Microthermal climates are found in higher latitudes and are characterized by cold winters, cooler summers, and a strong seasonal temperature variation.
• 😀 The increase in latitude in microthermal climates leads to shorter days in winter, diffuse solar radiation, and cooler temperatures due to continentality.
• 😀 Precipitation in microthermal climates is influenced by conflicting air masses in winter and convectional thunderstorms in summer.
• 😀 Examples of microthermal climates include humid continental and sub-arctic climates, with distinct temperature changes based on latitude and cold winters.

Q & A

What are mesothermal climates, and where are they typically found?

Mesothermal climates are found in the mid-latitudes and are characterized by mild winters. These climates cover about 27% of the Earth's surface and are home to over 40% of the world’s population. They are typically found in regions such as the United States, East Asia, and Western Europe.

Why is seasonality important in mesothermal climates?

Seasonality is important in mesothermal climates because it marks the shift from moderate to more extreme conditions as one moves away from the equator. These climates experience significant changes in day length and insolation, which influence temperature variations throughout the year.

What are the primary weather patterns in mesothermal climates?

Mesothermal climates are characterized by high weather variability and frequent interactions between air masses. These interactions create weather fronts, leading to varied precipitation patterns. The influence of shifting maritime and continental air masses also contributes to the climate's variability.

What is the role of air masses in mesothermal climates?

Air masses play a crucial role in mesothermal climates by migrating from their source regions and meeting in these areas, creating fronts. The interaction of these air masses, which carry specific characteristics from their source regions, significantly impacts the weather in mesothermal climates.

What is the climate like in humid subtropical regions?

Humid subtropical climates feature hot summers with warm, unstable maritime air that causes convectional showers over land. In other seasons, maritime tropical masses meet polar air masses, forming fronts and storms. An example of this climate can be found in the southeastern United States.

What distinguishes Mediterranean dry-summer climates from other climate types?

Mediterranean dry-summer climates are distinguished by their dry summers and wet winters. At least 70% of annual precipitation occurs during the winter months, and summer months are notably dry due to high-pressure systems blocking moisture-bearing winds. These climates are found in regions like California, Chile, and the Mediterranean.

Why are Mediterranean dry-summer climates considered rare?

Mediterranean dry-summer climates are rare because they are found in only a few specific regions of the world, including California, parts of Chile, South Africa, Australia, and the Mediterranean. The dry summers are caused by high-pressure systems that block moisture, while wet winters are more typical of these regions.

What are the main characteristics of microthermal climates?

Microthermal climates are found in mid and high latitudes and are characterized by cold winters. These climates experience cooler temperatures overall and are influenced by polar air masses. They comprise about 21% of Earth's surface and are mostly located in the Northern Hemisphere.

How does latitude affect microthermal climates?

In microthermal climates, the increase in latitude results in shorter days with less insolation in winter, and longer but less direct sunlight in summer. These factors lead to colder temperatures, especially during winter months, and cooler summers as one moves farther north in latitude.

What types of precipitation are found in microthermal climates?

Precipitation in microthermal climates is often caused by conflicting air masses in the winter, leading to storms and snow. In the summer, convectional thunderstorms can occur. This variation in precipitation patterns is influenced by both latitude and air mass interactions.